linux-kernel - Re: [PATCH 07/14] drm/nouveau: use drm_crtc_send_vblank

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Date:	Mon, 25 Apr 2016 09:01:10 +0200
From:	Mario Kleiner <mario.kleiner.de@...il.com>
To:	Gustavo Padovan <gustavo@...ovan.org>,
	dri-devel@...ts.freedesktop.org
Cc:	Gustavo Padovan <gustavo.padovan@...labora.co.uk>,
	David Airlie <airlied@...ux.ie>,
	Ben Skeggs <bskeggs@...hat.com>,
	Daniel Vetter <daniel.vetter@...ll.ch>,
	Ville Syrjälä <ville.syrjala@...ux.intel.com>,
	Dave Airlie <airlied@...hat.com>,
	Ilia Mirkin <imirkin@...m.mit.edu>,
	Thierry Reding <treding@...dia.com>,
	open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 07/14] drm/nouveau: use drm_crtc_send_vblank_event()

On 04/14/2016 07:48 PM, Gustavo Padovan wrote:
> From: Gustavo Padovan <gustavo.padovan@...labora.co.uk>
>
> Replace the legacy drm_send_vblank_event() with the new helper function.
>
> Signed-off-by: Gustavo Padovan <gustavo.padovan@...labora.co.uk>
> ---
>   drivers/gpu/drm/nouveau/nouveau_display.c | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/nouveau/nouveau_display.c b/drivers/gpu/drm/nouveau/nouveau_display.c
> index 7ce7fa5..973c2d9 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_display.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_display.c
> @@ -841,10 +841,12 @@ nouveau_finish_page_flip(struct nouveau_channel *chan,
>
>   	s = list_first_entry(&fctx->flip, struct nouveau_page_flip_state, head);

Hi Gustavo

>   	if (s->event) {
> +		struct drm_crtc *crtc = drm_crtc_find(dev, s->crtc);
> +

I don't think this would work. s->crtc is a nouveau internal display 
pipe index, not a drm mode object id, so i don't think drm_crtc_find() 
will do what you need. Also it takes a mutex, which might_sleep() and i 
think nouveau_finish_page_flip gets called from irq context and holds a 
spin_lock_irqsave, so would end badly.

You'd probably have to extend struct nouveau_page_flip_state to carry 
around a reference to the required drm_crtc, set up in 
nouveau_crtc_page_flip().

-mario

>   		if (drm->device.info.family < NV_DEVICE_INFO_V0_TESLA) {
>   			drm_arm_vblank_event(dev, s->crtc, s->event);
>   		} else {
> -			drm_send_vblank_event(dev, s->crtc, s->event);
> +			drm_crtc_send_vblank_event(crtc, s->event);
>
>   			/* Give up ownership of vblank for page-flipped crtc */
>   			drm_vblank_put(dev, s->crtc);
>